The Effect of HTML Compression on a PPP Modem Line

This document describes the possible benefits in performance when compressing
HTML files over a PPP modem line. See also the investigation on how
compression affects transport on a LAN. The purpose
of the test is to show the impact of using deflate on a HTML message body
and see if this is worth doing on top of normal modem compression.

Note that we only download the HTML page and not any of the
following images. The size of the uncompressed HTML page is 42K HTML
and the compressed was 11K. This means that we decrease the overall
payload with about 31K or 73.8%.

Default Modem Compression

I need some pointers here - I am not sure exactly what of which algorithms,
a standard 28.8 modem uses.

Summary

In our test case we observed a gain in time relative to number of TCP packets
as follows:

The table shows very similar data for both Jigsaw and Apache - around 2/3
saved in both packet count and time. Noting that the first TCP packets are
more important than later ones, based on these figures, the gain of using
compression is substantial.

The result may depend on how the modem performs compression and may vary
depending on the size of the HTML object. However, we believe that the
effect of HTTP message body compression will be positive on a PPP modem line.

This test does not take into account the time it takes to compress
an HTML object on the fly and whether this will take longer than the time
gained transferring less bytes. Decompression is done on the fly by the client.